1. Field on the Invention
This invention relates to a low crystalline oxytitanium phthalocyanine, an oxytitanium phthalocyanine of a novel crystal form obtained from the same and an electrophotographic photosensitive member using the same.
2. Related Background Art
Heretofore, phthalocyanine pigments have been regarded and studied as electronic materials for use in electrophotographic photosensitive members, solar cells, sensors, etc. besides coloring applications.
Non-impact type printers based on the application of the electrophotographic technique have been widely used as terminal printers in place of the conventional impact-type printers. The non-impact-type printers are mainly laser beam printers using a laser beam as a light source, where a semiconductor laser is used from the viewpoint of cost, size of apparatus, etc.
The semiconductor laser now mainly used has an oscillation wavelength which is as long as 790.+-.20 nm, and thus development of electrophotographic photosensitive members having sufficient sensitivity to the beams of such long wavelengths has been conducted to date.
The sensitivity of electrophotographic sensitive members mainly depends upon the type of charge generation materials used.
Recently, studies have been made much on such charge generation materials having a sensitivity to the beams of long wavelength as metal phthalocyanines and non-metal phthalocyanines, for example, chloroaluminum phthalocyanine, chloroindium phthalocyanine, oxyvanadyl phthalocyanine, chlorogallium phthalocyanine, magnesium phthalocyanine, oxytitanium phthalocyanine, etc.
The presence of various crystal forms is known in many of these phthalocyanine compounds. For example. .alpha.-type, .beta.-type, .gamma.-type, .delta.-type, .epsilon.-type, .chi.-type, .tau.-type, etc. are known in the non-metalphthalocyanines and .alpha.-type, .beta.-type, .gamma.-type, .delta.-type, .epsilon.-type, .chi.-type, etc. are known for copper phthalocyanine.
It is also known that differences in the crystal forms have a large influence upon the electrophotographic characteristics (sensitivity, potential stability on the durability test, etc.) and also upon the paint characteristics when the phthalocyanine compound is made into a paint.
Many crystal forms are also known for oxytitanium phthalocyanine as having a particularly high sensitivity to the beams of long wavelengtb, as in the case of non-metal phthalocyanines, copper phthalocyanine. etc. For example, Japanese Patent Application Kokai (Laid-open) No. 59-49544 (U.S. Pat. No. 4,444,861), Japanese Patent Application Kokai (Laid-open) No. 59-166959, Japanese Patent Application Kokai (Laid-open) No. 61-239248 (U.S. Pat. No. 4,728,592), Japanese Patent Application Kokai (Laid-open) No. 62-67094 (U.S. Pat. No. 4,664,997), Japanese Patent Application Kokai (Laid-open) No. 63-366, Japanese Patent Application Kokai (Laid-open) No. 63-116158, Japanese Patent Application Kokai (Laid-open) No. 63-198067 and Japanese Patent Application Kokai (Laid-open) No. 64-17066 disclose oxytitanium phthalocyanines of different crystal forms.
However, since the processes for producing the conventional crystal forms use A-type crystal as a stable type [Japanese Patent Application Kokai (Laid-open) No. 62-67094 (U.S. Pat. No. 4,664,997)] or B-type crystal as a semi-stable type [Japanese Patent Application Kokai (Laid-open) No. 61-239248 (U.S. Pat. No. 4,728,592), or acid-pasted A-type or B-type crystal as a starting material, it is very difficult to obtain a novel crystal form, because fine control is required as a production condition or a special treatment is required.